CARDIAC DYSFUNCTION WITH BECKER MUSCULAR-DYSTROPHY

Cardiac function was examined in 21 patients with Becker muscular dyst rophy (BMD) and compared with 43 patients with Duchenne muscular dystr ophy (DMD) and 37 healthy control subjects. Electrocardiography showed myocardial damage was most frequently found in the lateral wall, comp atible with autopsy findings. The ratio of the preejection period to t he ejection time was higher in patients with BMD (0.37 +/- 0.07, mean +/- SD) than in patients with DMD (0.28 +/- 0.05) and healthy controls (0.23 +/- 0.04). Left ventricular dimension and mitral annular size a t end diastole in patients with BMD increased to 52.3 +/- 7.7 mm and 2 8.8 +/- 5.3 mm with age, respectively. In patients with cardiac failur e and BMD, mitral regurgitation was observed at a rate of 66.7%. No de finite relation between the deleted locus of the dystrophin gene and c ardiac failure was found. Because motor dysfunction progresses more sl owly in BMD than in DMD, a prolonged work load on the morbid myocardiu m may lead to dilated cardiomyopathy with mitral regurgitation.